It's not clear to me where the word "helloworld" refers to in these examples. Can you please clarify when 'helloworld' refers to the component,controller,model,table,view or form? While following this, I've changed the name of my component, and when running this I get a 'call to member function getTable() on non-object'. It seems that I used the wrong name somewhere, but I have no idea where.
We're also introducing JForms and JFields. These are powerful and important, and warrant some richer explanation.
There is a change in /admin/views/helloworlds/tmpl/default_body.php that isnt mentioned on this page but is present in the archive file.